Humanity is unlikely to prevent the Earth from warming, at least temporarily, by 1.5°C above pre-industrial levels – but aggressive measures to curb greenhouse gas emissions and remove carbon from the atmosphere could limit the increase and bring temperatures back down latest report of the United Nations Intergovernmental Panel on Climate Change (IPCC). However, the report makes clear that the window is fast closing and with it the chance to prevent the worst effects of global warming. Above the 1.5°C limit – set by the 2015 Paris Climate Agreement – the likelihood of extreme weather and collapsing ecosystems increases.
“The IPCC tells us we have the knowledge and technology to do this,” said Inger Andersen, Executive Director of the UN Environment Programme, at a news conference for the release of the report. “But increased action needs to start this year, not next year, this month, not next month, today not tomorrow.”
The roughly 2,900-page report, adopted by 195 governments after a marathon of negotiations that ran two days ahead of schedule, focuses on options to curb emissions and mitigate the effects of global warming. The document, compiled by hundreds of scientists in 65 countries, is the latest in a trilogy comprising the IPCC’s sixth climate assessment, with the first two reports covering the underlying science and how climate is affecting people and ecosystems.
Multiple sources involved in the virtual session narrated nature that negotiations to finalize the report stalled as government delegates battle perennial bickering over climate change. The negotiators for India in particular have raised questions about the emissions scenarios in the report, arguing that they assume too much action by developing countries and do not adequately reflect issues of equity and responsibility. Negotiators for Saudi Arabia examined language related to carbon capture technologies and the future of fossil fuels. Although these debates have protracted negotiations, sources say they have not affected the results or distorted the underlying science in the report.
More than three decades after the panel’s first climate assessment, Part Six delivers the most stark warning yet of the consequences of inaction. The question now, say the scientists, is whether governments will finally meet the challenge with action rather than unfulfilled promises.
“Emissions continue to rise despite continued mitigation efforts by more governments at all levels,” said Karen Seto, a geographer at Yale University in New Haven, Connecticut, and the report’s coordinating lead author. “We still have a lot more to do, and we have to do it quickly.”
Key points from the report:
• This is one of the IPCC’s toughest warnings to date. The message? Time is almost up. Models suggest that global emissions must peak no later than 2025, and then fall rapidly, for the world to have a 50% chance of limiting warming to 1.5°C. CO2 emissions would also need to almost halve by 2030 and reach “net zero” in the early 2050s to reach the target. Given current policies, some scientists estimate the world is on track for a nearly 3°C rise from pre-industrial levels.
• But the report is not entirely bleak. While emissions continue to rise, there are also signs that some mitigation efforts have had an impact. Renewable energy technologies such as wind turbines, solar panels and batteries are falling in price and the world economy is becoming cleaner. Global energy intensity – a measure of the amount of energy needed to power the economy – fell by 2% annually between 2010 and 2019, reversing the trend of the previous decade.
• To prevent temperatures from significantly exceeding 1.5°C, some fossil fuels must remain in the ground. According to models that keep global warming just above this limit, emissions from existing and planned fossil fuel projects are already exceeding the allowable carbon budget.
• To meet the net-zero emissions targets they set, it’s not enough to cut emissions – they also need to extract carbon dioxide from the atmosphere. This offsets residual greenhouse gas emissions from sectors that are difficult to clean, such as industry or aviation. Nations could achieve carbon capture by expanding forests and improving agricultural practices, or through a variety of new technologies that can capture carbon emissions from either industrial sources or directly from the atmosphere.
• Despite concerns about the cost of mitigation, meeting climate targets won’t break the global bank: Models suggest global economic growth will continue for decades to come, even with aggressive action to curb emissions. Although global gross domestic product is projected to fall slightly by mid-century in scenarios where climate action was taken compared to scenarios where it was not, most research suggests that the economic benefits of mitigation of warming – including improved health and reduced climate – are harms – exceeding the mitigation costs.
• Still, wealthy nations must provide financial assistance to low-income countries to address climate vulnerability inequalities and accelerate the clean energy transition in ways that benefit all. The countries with the lowest greenhouse gas emissions are often hardest hit by climate change: the 88 countries that comprise the least developed country and small island developing country groups in the UN climate framework are collectively responsible for less than 1% of historical CO2 emissions.
The good news and the bad news
The report makes clear that current energy, economic and political trends are putting the world on track to overshoot warming well beyond 1.5°C. Scientists have long warned against this, but some say it’s time to think about what that means in terms of climate strategy.
“I think we are approaching a political situation in which we have to seriously ask ourselves how we are going to deal with this transgression,” says Oliver Geden, social scientist at the German Society for International Politics and Security in Berlin and coordinator of the report’s author. While it is technically possible to limit warming to 1.5°C, the action required would be unprecedented.
But the report also gives cause for optimism by highlighting climate technologies and policies that are already reducing emissions in many countries. The immediate goal is to accelerate that effort and increase climate funding to ensure it’s a truly global effort, says Nathaniel Keohane, president of the Center for Climate and Energy Solutions, an environmental think tank in Arlington, Virginia , and White House Advisor to former US President Barack Obama. In the longer term, governments need to invest in research and development activities to study the feasibility of carbon removal technologies that could help bend the curve in the coming decades.
“It’s a Herculean effort, so we better get started,” says Keohane.